Black-headed Gull Chroicocephalus ridibundus

(last update: 3-04-2011)

Below: First-calendar year Black-headed Gull E5RM, July 6, 2010, Benthuizerplas, Zoetermeer, The Netherlands (52.07N 04.53E). Photo: Maarten van Kleinwee.

First-calendar year Black-headed Gull, moulting to first-winter (formative) plumage. In this post-juvenile moult, all feathers are replaced except those on the wings and in the tail.

In this individual, the body is now almost completely white and the brown markings on the head and hind neck have started to fade. The scapulars and mantle feathers still show predominantly first-generation, juvenile brown feathers. P8 and P9 show extensive dark markings.

This individual was ringed as part of the Dutch RAS project (Recapturing Adults for Survival; research on survival of Dutch breeding birds).
For more information about the RAS project, visit http://frankmajoor.nl/kokmeeuwen-broedvogels1-uk.shtml.

Below: 1cy Black-headed Gull E5RM, July 27, 2010, Grote Dobbe, Zoetermeer, The Netherlands (52.059N, 4.494E). Photo: Maarten van Kleinwee.

At the end of July, the body in this individual has now turned almost completely white and the brown markings on the head have started to disappear, leaving head markings similar to that of an adult in winter (basic) plumage but with brown coloration instead of black. Still much brown can be seen in the hind neck. Gray, second-generation scapulars and mantle feathers are now starting to appear.